Seeing the round gripped LanCay M9-XM on ebay last week made me realize that I don't think the other variation has ever been featured here. When LanCay made the solid tang bayonets they produced the standard round grip (as seen in the auction) and a corresponding number of bayonets with green M7 style grips. Here are front and back views of the bayonets
Here are pictures of the blade markings on the two different variations; USMC and US Army
Nice pictures!
Strange enough, not only there is a visible difference in the scabbard configuration between the USMC and US Army versions, but note also the hyphen on Lan-Cay in the Army version.
There is not many information about these LanCays full tang.
The Brett book shows two of them, both with USMC markings.
Few notes ara available on the Frank Trzaska website.
Here http://www.usmilitaryknives.com/knife_knotes_2.htm (bottom page)
here http://www.oregonknifeclub.org/frank3.html (middle page with picture by Cole)
and here http://www.usmilitaryknives.com/knife_knotes_5.htm (in the middle, with picture of one USMC version).